我想使自定义对象可哈希化(通过酸洗)。我可以找到适用于 Python 2.x 的 __hash__ 算法(请参阅下面的代码)，但它显然不同于适用于 Python 3.2 的哈希(我想知道为什么？)。有人知道 __hash__ 在 Python 3.2 中是如何实现的吗？
#Version: Python 3.2
def c_mul(a, b):
#C type multiplication
return eval(hex((int(a) * b) & 0xFFFFFFFF)[:-1])
class hs:
#Python 2.x algorithm for hash from http://effbot.org/zone/python-hash.htm
def __hash__(self):
if not self:
return 0 # empty
value = ord(self[0]) << 7
for char in self:
value = c_mul(1000003, value) ^ ord(char)
value = value ^ len(self)
if value == -1:
value = -2
return value
def main():
s = ["PROBLEM", "PROBLEN", "PROBLEO", "PROBLEP"]#, "PROBLEQ", "PROBLER", "PROBLES"]
print("Python 3.2 hash() bild-in")
for c in s[:]: print("hash('", c, "')=", hex(hash(c)), end="\n")
print("\n")
print("Python 2.x type hash: __hash__()")
for c in s[:]: print("hs.__hash__('", c, "')=", hex(hs.__hash__(c)), end="\n")
if __name__ == "__main__":
main()
OUTPUT:
Python 3.2 hash() bild-in
hash(' PROBLEM ')= 0x7a8e675a
hash(' PROBLEN ')= 0x7a8e6759
hash(' PROBLEO ')= 0x7a8e6758
hash(' PROBLEP ')= 0x7a8e6747
Python 2.x type hash: __hash__()
hs.__hash__(' PROBLEM ')= 0xa638a41
hs.__hash__(' PROBLEN ')= 0xa638a42
hs.__hash__(' PROBLEO ')= 0xa638a43
hs.__hash__(' PROBLEP ')= 0xa638a5c
最佳答案
为什么他们不同的答案写在那里:
Hash values are now values of a new type, Py_hash_t, which is defined to be the same size as a pointer. Previously they were of type long, which on some 64-bit operating systems is still only 32 bits long.
哈希也考虑了要计算的新值，看看
sys.hash_info
对于字符串，可以看看http://svn.python.org/view/python/trunk/Objects/stringobject.c?view=markup第 1263 行 string_hash(PyStringObject *a)
关于python - __hash__ 在 Python 3.2 中是如何实现的？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/6008026/